This Animal Model Core will be responsible for ordering mice, scheduling their use, performing the various manipulations required to induce experimental colitis, maintaining a barrier facility on the 8th Floor Zeigler Animal Care Facility, performing routine surveys to insure absence of any pathogens in the colony, and assist in the harvesting of tissues from such mice. Centralization of these functions in an Animal Model Core will provide uniformity and quality control of mouse models being studied in the various projects, will reduce cost because each project will not have to prepare and maintain their own animals, and conserve numbers of mice by ensuring maximal use of each one in the various projects. Dr. Charles Elson will serve as Director and Dr. Kenneth Beagley will serve as co-Director of this Core. A sub-Core will be located at the Jackson Laboratory in Bar Harbor, Maine. Its purpose will be to develop new, mutant and transgenic mouse models of inflammatory bowel disease. Dr. Ed Birkenmeier of the Jackson Laboratories will serve as Director and Principal Investigator of this sub-Core. Two approaches will be taken at Jackson. In the first, mice from the production facility and from existing mutant strains at Jackson Laboratories will be screened for chronic diarrhea associated with blood or white cells in the stool. Mice with this trait will be checked for pathologic changes of colitis. Parents and siblings of such mice will be bred selectively to express colitis as a stable predictable trait. The number and location of genes responsible will then be mapped. In the other approach, transgenic technology will be used to express a foreign antigen in the intestinal epithelial cells using the promoter for the gene for the intestinal fatty acid binding protein. Syngeneic cells immunized to this antigen will be transferred into the transgenic mice to induce colitis.